1. Field of the Invention
The present invention relates to an image processing apparatus and imaging apparatus capable of performing a plurality of image processing operations in direct connection with each other.
2. Description of the Related Art
With the recent increase in the number of pixels and the improved sequential shooting performance of the imaging apparatus such as a digital camera, demand has grown for an image processing apparatus capable of processing the image data having a vast number of pixels within a short time.
A technique for increasing the image data processing rate has been proposed by Jpn. Pat. Appln. KOKAI Publication No. 2000-312327, for example, in which a plurality of image processing operations are processed in pipelined fashion. According to Jpn. Pat. Appln. KOKAI Publication No. 2000-312327, a plurality of stages of an image processing unit for executing a plurality of spatial filtering processes such as the low-pass filtering processes and an image compression processing unit are directly connected to each other. Also, in Jpn. Pat. Appln. KOKAI Publication No. 2000-312327, the image data is read from a frame memory in units of a block having as many pixels along the columns as along the columns of a compression unit (generally called MCU (minimum coded unit)) and one line of pixels along the rows so that the image data can be input to the image compression processing unit from the last stage of the image processing unit for each compression unit required to execute the compression process in the image compression processing unit.
In the case where the image data is subjected to the spatial filtering process, the image data after processing is generally reduced in size as compared with the image data before processing. This is due to the fact that the image processing operation such as the spatial filtering process cannot process the peripheral portion of the image data input to the image processing unit. In the configuration in which the image processing unit and the image compression processing unit are directly connected to each other as disclosed by Jpn. Pat. Appln. KOKAI Publication No. 2000-312327, the number of pixels along the columns of the image data input from the last stage of the image processing unit to the image compression processing unit is required to be rendered equal to the number (or an integer multiple of the number) of the pixels along the columns of the compression unit. For this reason, according to Jpn. Pat. Appln. KOKAI Publication No. 2000-312327, the peripheral portion of each block is processed in overlapped fashion at the sacrifice of a reduced image processing efficiency.
A technique to avoid the overlapping process on the image data in the spatial filtering process has been proposed by, for example, Jpn. Pat. Appln. KOKAI Publication No. 2002-304624. According to this patent application, the intermediate data of the overlapped portion being processed in the filter processing means and to be used also for processing the next division image is stored in a frame memory (image memory), and by processing the next division image using the particular next division image and the intermediate data stored in the frame memory (image memory), the requirement of processing the overlapped portion a plurality of numbers of times is eliminated.